Partial support is requested for a conference on chromosome structure and segregation sponsored by the American Society for Cell Biology, to be held at Airlie House, Airlie, VA on September 8-12, 1989. The purpose of the conference is to convene in one small meeting the students of diverse aspects of chromosome behavior: replication initiation, stability, condensation and segregation. Customarily, interaction among these groups of scientists is infrequent. For example, scientists studying chromosome recombination do not usually meet with those studying chromosome movement. However, people from these disciplines have much to teach one another that will be mutually beneficial for the understanding of chromosome behavior. We expect that improved communication should lead to synergistic scientific activity that will in turn be helpful to both medicine and basic science. We plan a four day meeting comprising seven scientific sessions of invited platform presentations, a poster session that will last for the duration of the meeting, and one technical workshop. Everyone who comes will make a presentation in one of these formats. The platform sessions and their chairs will be (1) Segregation elements and their proteins [John Carbon]; (2) Replication origins, telomeres, and their proteins [Elizabeth Blackburn]; (3) Mitotic prophase and its control [Gary Borisy]; (4) Pairing, recombination, and segregation in meiosis [Adelaide Carpenter]; (5) Prometaphase: spindle assembly and chromosome congression [Edward Salmon]; (6) Anaphase; forces that separate the chromosomes [Bruce Nicklas]; and (7) Control of cell division [Mark Kirschner]. The technical workshop will be on fluorescence methods for in situ hybridization and for the measurement of cellular ionic transients [Lansing Taylor]. The conference schedule will be constructed to maximize communication between the groups of scientists that do not normally meet. The more cell biological sessions will be laced with talks featuring molecular biology and genetics, and vice versa. There will be time on two afternoons for informal meetings and discussions. The more experienced scientists who will make up the majority of the platform speakers will interact with those who present posters.